My mom had it. It was really painful for her. Sharp pains for over a year before she was diagnosed. Couldn't run. But could swim and ride a bike... sort of. Had surgery and is much better, but is dealing with other injuries now like ITBS and piriformis stuff, probably from overcompensating from her knee injury for so long.
Ugh - mine was a nightmare. It was a partial tear, diagnosed by a MRI. They didn't want to do surgery to cut through healthy meniscus, but the pain was awful. I had to take pain meds for two months every night to sleep. Cortisone shots did absolutely nothing. They finally went in and removed a bunch of scar tissue and poked some holes in the meniscus to promote healing, but even now - a year later - my knee still isn't the same.
A meniscus tear needs a MRI for an official diagnosis. Are you getting any catching or locking up of your knee like where you need to force it to straighten or bend? This is a good indicator of a meniscus tear. The inner portion of the meniscus does not have a good blood supply and will not heal on its own. With an isolated tear, they will often go in and cut out the torn portion. Recovery time is usually pretty quick with this. The outer portion does get some blood supply. Some doctors will repair this. This recovery is much longer as you need to be non weight bearing for awhile to protect the repair.